U.S. Pat. No. 4,912,011 discloses a light-sensitive material comprising a support and a light-sensitive layer provided thereon which contains silver halide, a reducing agent, a polymerizable compound and a color image forming substance. The silver halide, the reducing agent, the polymerizable compound and the color image forming substance are contained in microcapsules (light-sensitive microcapsules) which are dispersed in the light-sensitive layer. The U.S. Patent corresponds to Japanese Patent Provisional Publications No. 61(1986)-275742 and No. 61(1986)-278849 and European Patent Provisional Publication No. 0203613A.
An image forming method using the light-sensitive material is also disclosed in U.S. Pat. No. 4,912,011. The method comprises the steps of imagewise exposing the light-sensitive material, and heating the light-sensitive material. A latent image of the silver halide is formed by the exposure. The polymerizable compound is polymerized by heating within the area where the latent image has been formed. The light-sensitive material is then pressed on an image-receiving material to transfer the unpolymerized polymerizable compound with a color image forming substance to the image-receiving material to form a color image on the image-receiving material.
Further, a method of polymerizing the polymerizable compound within the area where the latent image of the silver halide has not been formed is disclosed in Japanese Patent Provisional Publications No. 61(1986)-243449, No. 61(1986)-260241, No. 2(1990)-141756 and No. 2(1990)-141757. The contents of the former two publications are described in European Patent Provisional Publication No. 0202490A.
The development and polymerization reactions smoothly proceed in alkaline conditions. Therefore, the light-sensitive material preferably contains a base precursor as an image forming accelerator. The base precursor is more preferably incorporated into light-sensitive microcapsules, as is described in U.S. Pat. No. 4,939,064 (corresponding to Japanese Patent Provisional Publication No. 64(1989)-32251 and European Patent Provisional Publication No. 0301539A) and Japanese patent Provisional Publications No. 1(1089)-263641, No. 2(1990)-146041 and No. 2(1991)-25444. The base precursor is composed of a salt of an organic base with a carboxylic acid, and is generally used in the form of solid particles.
With respect to a color image forming substance, the pigment particles have recently been used to obtain a stable color image. Accordingly, in the recent embodiment of the light-sensitive material, silver halide, a reducing agent, pigment particles, a polymerizable compound and a base precursor are contained in microcapsules which are dispersed in the light-sensitive layer.